An extensive body of prior art exists disclosing the use of a myriad of cured epoxy systems in coatings, composite matrices, casting resins, adhesives and the like (Cf. Encyclopedia of Polymer Science and Technology, Vol. 6, pages 209-271, Interscience Publishers, New York City, 1967).
Copolymers of the diglycidyl ether of bisphenol A and aminopropyl-terminated aliphatic siloxane oligomers were demonstrated by J. L. Hedrick and co-workers to have a two-phase morphology ["Synthesis and Properties of Segmented Poly(hydroxyether-siloxane Copolymers", Polymer Preprints, Vol. 27, No. 2, National ACS Meeting, Anaheim, Calif., 203 (1986)]. The maximum Tg observed in this study was 27.degree. C. No preparation of epoxy/silicone polymer systems has been reported in the prior art where the maximum Tg is in the region of 100.degree. C.
As the use of epoxy resins is extended, more stringent physical property requirements arise with each new application. One new demanding application for epoxy resins is as a coating or adhesive for composite materials resistant to atomic oxygen attack in an outer space environment. In addition, this application requires the material to withstand severe thermal cycling (-70.degree. C. to +70.degree. C.) over extended periods of time.
It has been shown that some silicone-containing materials have improved resistance to atomic oxygen (Advanced Composites, November/December, page 33, 1986).
It is therefore an object of this invention to provide an epoxy resin composition having compatible components which can be cured to hardened products without phase separation and having a Tg of at least about 100.degree. C. or more.
It is still another object to provide siloxane-based epoxy adhesives that are more resistant to attack by atomic oxygen than conventional epoxy resins.
It is another object to provide cured epoxy resins having enhanced impact strength and moisture resistance.
Other objects will become apparent to those skilled in the art upon a further reading of the specification.